1. Field of the Invention
The present invention relates to a rotating machine provided with a sleeve molded of a porous material and a method of producing the rotating machine.
2. Description of the Related Art
There is a demand for further miniaturization and higher density of rotating machines, such as a hard disk drive. In response to the demand, in a rotating machine in which data is recorded, for example, magnetically, data is read and written with a magnetic head tracing over a recording disk through a slight gap between the two while the recording disk is being rotated at high speed. In the rotating machine, the recording disk and magnetic head are housed in a sealed housing space.
Japanese Patent Application Publication No. 2009-74572 discloses a fluid dynamic bearing having both a base with a communication hole communicating with ambient air and a sleeve that is made of a sintered member and fixed to the communication hole of the base. Part of the sleeve of the fluid dynamic bearing is exposed to ambient air.
In response to the miniaturization and higher density, the housing space in the rotating machine is filled with clean air in order to suppress the floating amount of the magnetic head. When a sleeve made of a sintered member is exposed to ambient air, there is the possibility that the clean air may leak out via the pores in the sleeve, even if the communication hole of a base is filled in by the sleeve as in the technique disclosed in the aforementioned Japanese Patent Application Publication.